1. Field of the Invention
The present invention relates to a mobile communications terminal, and particularly, to an antenna apparatus and an operation method thereof capable of actively coping with changes in the usage environment and the communications environment of a mobile communications terminal.
2. Background of the Related Art
In general, mobile communications terminals are being implemented with various types of antennas, namely, internal antennas or external antennas so as to acquire better quality in communications according to a communications environment.
FIG. 1 illustrates a related art internal antenna structure used in mobile communications terminals (hereinafter, referred to as just ‘terminal’) (e.g., a CDMA terminal, a GSM terminal, relatively small-sized handsets, etc.).
Referring to FIG. 1, an internal antenna 101 is installed at a particular upper space within a terminal, and connected to a Radio Frequency (RF) circuit via a matching circuit 102.
Similar to an external antenna, the internal antenna 101 is designed to allow communications with optimal performance at a designated frequency band (i.e., a transmission/reception band). The internal antenna 101 is advantageous considering the design (i.e., the appearance or aesthetics) of a terminal, but requires addition space (room or area) to allow installation within the terminal. That is, the required length of the internal antenna 101 (i.e., the “electrical” length, namely, the overall length of the entire antenna that is required for properly handling the transmitting and receiving of signals) must be made differently according to the particular frequency at which the terminal uses to operate. As a result, the space required for the internal antenna installation is determined according to a frequency band of the terminal. For example, a greater antenna length is required as the frequency band becomes smaller, and thus, the overall size of the internal antenna 101 should be increased in its design.
Many terminals being currently developed and released that support dual-band or multi-band frequency operation need to operate at various frequency bands, and thus the required space (room or area) to install the internal antenna 101 in such terminals is much greater than that of a terminal operating at a single frequency band.
However, the performance of an internal antenna is decreased by more than 2˜3 dB when compared with that of an external antenna, because of its limited installation space within the terminal and due to the operation environment of the terminal. In particular, although recent trends require the implementing of frequency band multiplexing capabilities (e.g., tri-band, quad-band, etc.) into a terminal, there are many difficulties in implementing such features into a terminal having an internal antenna when compared with a terminal having an external antenna. This is because it is difficult to ensure sufficient space around the internal antenna, and interference from the user's hand during usage occur more frequently when using a terminal having an internal antenna compared with a terminal having an external antenna.
Furthermore, in addition to the performance aspects of the terminal, because the internal antenna is installed within the terminal, the overall size of the terminal itself needs to be increased by an area required to accommodate the internal antenna. To overcome these problems, in the related art terminals having an internal antenna, several circuits need to be removed in order to provide enough space to install the internal antenna or the internal antenna design must be improved in order to reduce the overall size of the terminal.